Isso significa que `item` pode ser um `int` ou um `str`.

#### Possivelmente `None` { #possibly-none }

Você pode declarar que um valor pode ter um tipo, como `str`, mas que ele também pode ser `None`.

//// tab | Python 3.10+

```Python hl_lines="1"
{!> ../../docs_src/python_types/tutorial009_py310.py!}
```

////

}

// ErrFilterNamePrefix - more than one prefix usage error.
type ErrFilterNamePrefix struct{}

func (err ErrFilterNamePrefix) Error() string {
	return "more than one prefix in filter rule"
}

// ErrFilterNameSuffix - more than one suffix usage error.
type ErrFilterNameSuffix struct{}

func (err ErrFilterNameSuffix) Error() string {
	return "more than one suffix in filter rule"
}

                  @Override
                  SetMultimap<String, Integer> filter(SetMultimap<String, Integer> multimap) {
                    multimap.put("one", 314);
                    multimap.put("two", 159);
                    multimap.put("one", 265);
                    return filterValues(
                        multimap, not(Predicates.in(ImmutableSet.of(314, 159, 265))));
                  }
                })

 */

package com.google.common.collect.testing.testers;

import static com.google.common.collect.testing.features.CollectionFeature.SUPPORTS_REMOVE;
import static com.google.common.collect.testing.features.CollectionSize.ONE;
import static com.google.common.collect.testing.features.CollectionSize.ZERO;

import com.google.common.annotations.GwtCompatible;
import com.google.common.collect.testing.features.CollectionFeature;

        // Verify instance def is SESSION
        assertEquals(InstanceDefFactory.SESSION, pagerCreator.getInstanceDef());

        // Verify auto binding def is NONE
        assertEquals(AutoBindingDefFactory.NONE, pagerCreator.getAutoBindingDef());
    }

    // Test getPagerCustomizer when no customizer is set
    @Test
    public void test_getPagerCustomizer_null() {

              task.replaceValueInMatch("_source.values", ["z", "x", "y"], "one")
              task.removeMatch("_source.blah")
              task.removeMatch("_source.junk", "two")
              task.addMatch("_source.added", [name: 'jake', likes: 'cheese'], "one")
              task.addWarning("one", "warning1", "warning2")
              task.addWarningRegex("two", "regex warning here .* [a-z]")

  }

  public void testToArray() {
    // need explicit type parameter to avoid javac warning!?
    List<Float> none = Arrays.<Float>asList();
    assertThat(Floats.toArray(none)).isEqualTo(EMPTY);

    List<Float> one = Arrays.asList(1.0f);
    assertThat(Floats.toArray(one)).isEqualTo(ARRAY1);

    float[] array = {0.0f, 1.0f, 3.0f};

    List<Float> three = Arrays.asList(0.0f, 1.0f, 3.0f);

  }

  public void testToArray() {
    // need explicit type parameter to avoid javac warning!?
    List<Integer> none = Arrays.<Integer>asList();
    assertThat(Ints.toArray(none)).isEqualTo(EMPTY);

    List<Integer> one = Arrays.asList((int) 1);
    assertThat(Ints.toArray(one)).isEqualTo(ARRAY1);

    int[] array = {(int) 0, (int) 1, (int) 0xdeadbeef};

  }

  public void testToArray() {
    // need explicit type parameter to avoid javac warning!?
    List<Float> none = Arrays.<Float>asList();
    assertThat(Floats.toArray(none)).isEqualTo(EMPTY);

    List<Float> one = Arrays.asList(1.0f);
    assertThat(Floats.toArray(one)).isEqualTo(ARRAY1);

    float[] array = {0.0f, 1.0f, 3.0f};

    List<Float> three = Arrays.asList(0.0f, 1.0f, 3.0f);

這種情況下，你可以設定 `response_model=None` 來停用回應模型的產生：

{* ../../docs_src/response_model/tutorial003_05_py310.py hl[7] *}

這會讓 FastAPI 略過回應模型的產生，如此你就能使用任何你需要的回傳型別註解，而不會影響你的 FastAPI 應用程式。🤓

## 回應模型編碼參數 { #response-model-encoding-parameters }

你的回應模型可能有預設值，例如：

{* ../../docs_src/response_model/tutorial004_py310.py hl[9,11:12] *}

* `description: Union[str, None] = None`（或在 Python 3.10 中的 `str | None = None`）預設為 `None`。